14 SEER, 80% AFUE, 90% AFUE - don't get too confused by trying to figure out where
all the numbers come from. All you really need to know is that these are relative
measures of fuel economy—SEER (Seasonal Energy Efficiency Ratio) numbers for
air conditioners, or AFUE (Annual Fuel Utilization Efficiency) for gas furnaces.
In simplest terms, the higher the number, the more heating or cooling you'll get
for your energy dollar.
As you shop around, use the numbers, not vague terms like "high efficiency" or "super
high efficiency," to really compare systems. Any air conditioner or furnace on the
market today can be called "high efficiency" compared to the equipment of just a
few years ago. What was called high efficiency then—say 9 SEER for an air
conditioner or 70% for a gas furnace—wouldn't even be permitted on the market
today!
